The invention relates generally to hybrid and electric vehicles, and more specifically to a system and method of energy management and optimization of energy storage component usage aboard hybrid and electric vehicles.
Electric vehicles and hybrid electric vehicles are typically powered by one or more energy storage devices, either alone or in combination with an internal combustion engine. In pure electric vehicles, the one or more energy storage devices power the entire drive system, thereby eliminating the need for an internal combustion engine. Hybrid electric vehicles, on the other hand, include energy storage device power to supplement power supplied by an internal combustion engine, which greatly increases the fuel efficiency of the internal combustion engine and of the vehicle. Traditionally, the energy storage devices in electric or hybrid electric propulsion systems include batteries, ultracapacitors, flywheels, superconducting magnetic energy storage devices, or a combination of these elements in order to provide sufficient energy to power an electric motor.
When two or more energy storage devices are used to provide power to the drive system, the energy storage devices are typically well-suited to provide different types of power. A first energy storage device, for example, may be a high specific-power source more efficient at providing short-term power while a second energy storage device may be a high specific-energy storage device that is more efficient or economical at providing long-term power. The high specific-power energy storage device may be used to assist the high specific-energy energy storage device in providing power to the system during, for example, acceleration or pulsed load events.
It is desirable in such dual energy storage device arrangements to provide load-leveling functionality so as to reduce transient loading to the devices. However, prior art energy storage device arrangements generally operate with limited or no information about the environment and vehicle usage and lack a sophisticated control scheme. This often results in sub-optimal usage of the energy storage devices that can shorten life because of unnecessary applied stresses, with efficiencies of the energy storage devices not being optimized during charging and discharging events. Additionally, energy storage devices are over-sized for the application to ensure that stress limits are not exceeded, which adds cost to the system.
It would therefore be desirable to have a system and method capable of optimizing the usage and flow of energy from and to energy storage devices in an electric or hybrid power system.